Method of perforating sheet metal



Sept. 19, 1933. BALFE 1,927,791

METHOD OF PERFORATING SHEET METAL Filed Dec. 11, 1931 3 Sheets-Sheet l Zhwentor Gttornegs Sept. 19,1933. G. T.BALFE METHOD OF PERFORATING SHEET METAL Filed Dec. 11, 1931 3 Sheets-Sheet 2 w l a 1 l I I I y i1 a q ,I 7

(Ittornegs Patented Sept. 19, 1933 UNITED STATES 1,927,791 METHOD OF PERFORATING SHEET METAL George T. Balfe, Detroit, Mich., assignor to Detroit Gasket & Mfg. Company, Detroit, Mich., a corporation of Michigan Application December 11, 1931 Serial No. 580,415

4 Claims.

My invention relates to improvements in the perforating of sheet material such as metal sheets. It has particular reference to an improved process of perforating sheet material 5 such as metal, and more particularly to the forming of a large number of closely adjacent apertures in such a sheet, and in such a manner as not to remove any of the metal from the sheet and to give form and shape to the metal about the perforation.

An object of my invention is the manufacture of closely perforated sheet metal plates rapidly and economically, and the invention comprises a new process of their manufacture.

It is shown as embodied in mechanism for producing a reticulated metal sheet having a particular type of perforation and wherein the sheet is punched from opposite sides by substantially tooth-like members to produce apertures including oppositely directed minute tangs closely spaced from one another throughout the entire surface area of the sheet on both sides thereof and arranged after a specific fashion.

It is an object of this invention to produce a metal sheet of this character having closely spaced openings or perforations and barriers or walls adjacent said openings, by a method wherein (a) the metal is pierced, (b) the piercing operation continued in a manner to cut a narrow portion of the metal in advance of each tooth at one side of each opening substantially in the plane of rotation of the teeth, and (c) this severed portion is pressed laterally to form an elongated wall adjacent the opening and of relatively greater length than any of the remaining wall portion.

There are numerous uses to which sheet metal so perforated may be placed. One such use is as a base or reinforcement for gaskets as described and claimed in my copending application Serial No. 420.331, filed January 13. 1930, and Patent 1,776,140, issued September 16, 1930. As shown and described in such patent, a steel sheet formed with closely compacted barrier-like heat conducting projections in the nature of protuberances and tangs has these projections embedded in layers of gasket material, such as sheet asbestos, by pressure. The walls of the openings or protuberances at one side thereof are extended or elongated forming a freely deformable narrow tang portion which extends out from or beyond remaining adjacent side or opposite side wall portions. That is to say, the wall of the opening at one side thereof is extended or elongated and deformable to constitute a spring-like clenchable tang.

It is desirable that the walls or tangs project from opposite faces in a uniform style and arrangement and that they be formed without otherwise fracturing the metal and that the sheet so perforated retain sufficient strength for the purpose for which it is to be employed.

Consequently I have provided a method of producing such sheets by which the perforations may be formed in succeeding rows, all perforations in a row being simultaneously formed, and the adjacent perforations of each row being formed from opposite sides of the sheet so as to produce spaced tangs along each row which alternately project from opposite sides to produce the aforenamed results.

My improved machine includes a plurality of individual punch unit members provided with male punches so disposed in the relative arrangement of the several units as to carry out the desired process. The several punch unit members are arranged to act upon a sheet of metal to form successive rows of perforations therein.

Preferably the punch unit members are in the form of individual sheet steel discs having peripheral punch teeth and secured in a row in so closely spaced arrangement upon a rotatable arbor. A similar cooperating opposed arbor carrying similarly arranged discs is here illustrated with the discs of the two arbors enmeshed. Each disc, in its punch teeth, embodies a male die and a portion of a female die.

Arranged between each adjacent pair of discs is an individual sheet metal stationary stripper plate which serves to strip the metal sheet from the male dies of the rotating disc. These strip- 9 per plates are individually removable as are the discs and they are also arranged in pairs, spaced apart in the same plane, a pair between each pair of spaced discs on an arbor. Due to the enmeshed cooperation of the discs each pair of stripper plates is disposed between a pair of spaced discs on each arbor.

The stripper plates establish a planar guide for the metal sheet being acted upon by the discs. They also strip the plate after perforation from I the discs. Each line or row of stripper plates, the edges of which form a planar guide, act as an anvil for the opposed discs and cooperate with the female die portions of the adjacent rotatable discs to form the female dies.

A further object of the invention is to so present the respective male and female dies of the discs to each other that a clearance between each male and female die is provided during their interengagement whereby the metal is depressed and perforated to produce tangs and the tangs given a formats the process continues.

An additional feature of the invention resides in the means employed for distributing a cooling agent, usually a lubricant such as oil, upon the die members, and the provision of means for wiping or cleaning the sheet metal after it has been acted upon by the die members, to remove any film of cooling material which may be coated or have collected thereon and thus present the finished material in condition for subsequent operations without further treatment.

Other meritorious features of my improved method and machine will be obvious from the following description taken in conjunction with the drawings wherein:

Figure 1 is a cross section on the line l1 of Figure 2.

Figure 2 is a vertical section along the line 22 of Figure 1.

Figure 3 is a section along the line 3-3 of Figure 2.

Figure 4 is an enlarged section along the line 4-4 of Figure 2.

Figure 5 is a detail view in section showing the engagement of the die members.

Figure 6 is a detail view showing the action of the die members upon the sheet of material being treated.

Figures 7, 8, 9 and 10 are detail views of'the die member and associated parts.

My punch machine comprises a base or frame 10 having upright standards 12 and 14. These standards provide bearings for two opposed rotatable arbors 16 and 18. Each of these arbors is provided with gear wheels 20 and 22 which-are of identical diameter and possess the same number of teeth. Arbor 18 is driven through gear 22 from a suitable power source as by means of a chain, and the two arbors 16 and 18, therefore, rotate at the same rate or speed.

Secured transversely across the front and rear of the uprights 12 and 14, as by means of screws 26, are spaced keyway members 28 and 30. Similarly disposed keyway members 32 and 34 are secured to the opposite sides of the upright standards in a like manner. A guide and feed plate 36 is secured by means of the bracket 38 to the keyway 28 and assists in feeding the metal strips between the shafts 16 and 18.

Keyed to the keyways 28, 30, 32 and 34 and freely surrounding or partially embracing each of the shafts l6 and 18 to permit free rotation of the shafts with respect thereto, at closely spaced apart intervals along each of the said shafts, are my stripping discs 40 having keyways 40', as shown in Figures '7 and 10. The apertures 42 where a disc, as shown in Figure 7, is employed, are somewhat elongated for purposes to be hereafter brought out. Spacing discs or bearing washers 44 are keyed to the shafts 16 and 18 by means of keys 24 fixed to the arbors within the apertures 42 of stripping discs 40. These two discs occupy the same plane, but the spacing disc 44 is of infinitesimally greater thickness than the stripping disc 40. It may, however, assume various thicknesses as occasion may require.

The punching discs 46, about the circumference of which the punch teeth 48 are arranged are keyedto the shafts 16 and 18 and held in spaced relationship thereon by the spacing discs- 44. As illustrated in Figures 3, 4 and 5, the teeth 48 of the two discs 46 on each side of each spacing disc 44 are disposed in staggered relationship to each other. The punch discs, of course, revolve as a unit with the arbor upon which they are mounted.

As already stated, the apertures 42 in the stripping discs 40 are slightly elongated as shown at 41 in order that their peripheral edge will be subjected to minimum pressure and frictional wear from the rotating spacing disc or bearing Washers 44 which ride therein. This is shown best in Figure 5.

It will be seen from Figures 2 and 3 that the cooperating punch discs 46 keyed to the two shafts 16 and 18 occupy the same plane and mesh with one another. The male dies of one disc cooperate with the adjacent stripper discs to perforate the metal sheet. In the operation of the machine as the metal sheet is fed along the guide plate 36 it is caught by the teeth of the rotating punch discs. A bevel 50 is provided at the front of the straight edge portion of each of the stripping discs 40 to facilitate the ingress of the metal sheet. Inasmuch as the teeth 48 mesh and are being rotated in opposite directions, it will be seen that the sheet of metal will be punched alternately in opposite directions by each upper and lower pair of punch discs 46 as it progresses. It will also be seen that, inasmuch as the teeth 48 of the punch discs 46 which are located on opposite sides of the stripping discs 40 are staggered, the apertures punched in the sheet of metal and extending in a row will be staggered transversely across its width. The rows are punched and formed in succession.

The metal which is displaced by the piercing operation to form the aperture is not removed from the sheet and since the punch teeth 48 are rotating at the moment they commence their punching operation on the sheet of metal, the.

punch produces a small tang in the metal on the side opposite that from which it is punched. It is this tang, in contradistinction to a clean cut aperture, which renders the resultant sheet of metal particularly adaptable as a base unit for the gasket described in my aforesaid application. The projecting elongated walls or tangs and the remaining walls or sides of the apertures are given a substantially curved shape or inclined as shown in the copending application herein referred to and it is believed that this results from.

the rolling action of the teeth over the sheet, and that the sheet is first deformed and the metal partially shaped for the resulting aperture and tang before the metal is actually pierced and that following the piercing the tang is further bent and shaped. In other words, the tooth members deform the metal and there takes place a piercing at each point of engagement of a tooth with the side of the sheet forming openings and Walls (or protuberances) extending laterally from the opposite side of the sheet adjacent the openings The piercing is continued and a narrow portion of the metal in advance of each tooth is cut at one side of each opening substantially in the plane of rotation of the teeth, forming a substantially cup-shaped projection having one wall extended. This extended portion is pressed laterally from the said opposite side of the sheet formingthe elongated wall constituting a free deformable tang portion extending beyond the remainder of the wall of the opening, for example that at the adjacent or opposite side of v the opening and shaped to extend over the opening. This operation will be readily understood from the previous description and by reference to Figure 2 and Figure 3 of the drawings, as well as Figures 5 and 6 thereof.

Each row of stripping discs not only functions to strip the metal sheet from the. rotatable discs but it also functions as an anvil to receive the thrust of the opposed row of rotating punch discs. In addition it also serves to cooperate with the female die portions of the adjacent row of rotating punch discs to form the complete female dies for the male dies of the opposed row of rotating punch discs.

A receiving plate 52 is mounted upon a second bracket 54 which is secured to the keyway 34 on the egress side of the punch machine, and the end of the straight edge portion of each of the stripping discs 40 is cut away as at 56 for the purpose of freeing up the sheet of metal as it issues from the rotating punch discs.

In' the drawings, particularly in Figure '7, I have illustrated the slight elongation of the apertures 42 in the stripping discs 40, and have indicated this at 41.

The arbors are adjustable toward or from each other to provide for movement of one or both arbors. Preferably the upper arbor is made adjustable by means of spacer blocks mounted in the frame and supporting the bearing blocks. Suitable means are provided for firmly securing the arbor in any one of its adjusted positions, as for example spacer blocks may be disposed in the frame above the bearing blocks, and by means of adjustable screws or bolts suitably tightened to hold the bearing blocks between the spacer to dispose the opposed meeting edges of the.

stripper plates in the proper vertical spaced apart relation. By using arcuate or semi-circular plates, any possibility of wear, due to'friction between the plate and the piercing disc, is eliminated.

It will thus be seen that the arbors and stripper plates may be adjusted to vary the depth of the depression and the length of the tang as required.

It will be understood that, while the machine is operated at relatively high speeds, the treatment of the metal is gradual so far as the bending, piercing and forming operations are concerned. This will be readily understood from Figure 5, where there is a gradual bending to the center, piercing and a gradual forming at the center to produce openings having elongated walls constituting tangs or deformable portions.

It will be observed that the stripper plates 40 illustrated in detail in Figure 10 are provided with recesses 60 in the side edges thereof adjacent the lower edge. The recesses 60 receive the respective keyways 28, 30, 32 and 34 and are vertically adjustable towards or away from each other, by reason of the said keyways being slidably mounted in a vertical direction on the.frame of the machine.

I may use either a stripper member of the form illustrated in Figure 7, but prefer to use a stripper member 40 of the type illustrated in the drawings and in detail in Figure 10. By employing a stripper member as shown in Figure 10 of this application, the respective stripper members are adjustable with respect to the arbors within very delicate limits without moving the arbors and it is only where spacing of the stripper members is extended that the arbors need be moved; at the same time a great saving in metal is obtained.

Referring to Figure 2, I disclose nozzles 63 and 64 at the feed in side of the machine adapted to throw a spray of lubricant and cooling medium upon the die members and associated parts. On the other side of the machine, I disclose a blast apparatus which acts to remove any cooling medium or lubricant which has formed as a film upon the perforated sheet. Thus the sheet is caused to pass beneath a blast hood 64 having an enlarged outlet and over a transversely disposed grid 66 having a dimension substantially thatof the blower outlet 65. The grid 66 will support the perforated material and the action of the blast 64 is to force any lubricant upon the perforated plate or within the openings and projections downwardly into the outlet 67 communicating with the mouth of the grid 66. A suitable suction fan is connected to the outlet 67 and, therefore, the sheet is not only acted upon on its upper surface by the blower, but

is subjected to a suction on its under-surface so that a thorough cleaning is obtained. The lubricant is delivered from the outlet 6'? to a suitable collector, not shown, whence it may be pumped back and. 're-used. The blower and grid substantially enclose a sheet of formed material delivered from the machine, being of sulficient transverse dimension for this purpose.

The surface of grid 66 is flush with receiving plate 52 as shown in Figure 2.

It will be observed that the grid which preferably consists of a plurality of transversely or longitudinally spaced bars is substantially flush with the stripper "plates forming therewith a continuous path, whereby the sheet is not subjected to any bending or otherwise distorted. Furthermore, the cleaning action takes place at once as a part of the continuous operation of forming the sheet being immediately subsequent. to the deliveryof the sheet from the die members.

A pan 661s disposed at the base of the machine to collect any'of the cooling medium which drips therefrom. \f g;

It is to be observed that by reason of the construction employedthat the punching operation is a continuous process involving the steps of forming the depressions i. e. deforming the metal, piercing a portion of the bottom of each depression and continuing the cutting at one side of the opening as above described to produce thereby an elongated wall at said side of the opening constituting a tang and then simultaneously giving form-and shape to the uncut wall of the depression and to the tang, whereby a protuberance having a tang extending beyond the plane of the sheet is formed. In other words, a walled opening is produced by reason of the deformation maintain undistorted the space between the respective projections, so that the plane of the sheet is not changed.

I desire to refer particularly to Figure 2 and Figures 5 and 6. It is to be observed upon reference to Figure 5 that the intermeshing teeth 48 engage each other, whereby a clearance is provided. Thus, in Figure 5, it will be noted that initially the point of the male die bears against the right side of the female die. leaving a space between the left sides of the respective die members. As the rotary motion of the die members progresses the space between each side of the male die and each side of the female die becomes equal and then the tooth point moves toward the left side of the female die, whereby a space is created between the right side of each die. In this manner, the metal is first deformed or depressed by engagement of the tooth member (see first indentation at the right of Figure 6) and thereafter perforated (see next succeeding indentation toward the left of Figure 6) and the metal at the bottom of said depressed portions is formed into a tang extending beyond the plane of the sheet (see other perforations to the left of Figure 6). It will be noted that the metal is first deformed, then pierced and the piercing continued to cut a narrow portion in advance of each tooth substantially in the plane of rotation of the teeth, thereby forming the is not removed, but instead formed into a tang greater length than the wall at the opposite side of the opening as clearly shown in Figure 6. In other words, the initial action of the die members is to depress the metal forming closed protuberances and thereafter the bottom of such protuberances is pierced and perforated by the teeth of the dies and the metal of such bottom out in its passage through the machine by reason which, as stated, is beyond the plane of. the sheet material and forms an elongated wall of the opening or the protuberance of greater length than remaining wall portions of the protuberances, for example that of the wall portion at the opposite side of the opening and inclined to extend partially over the opening. This rolling motion after the piercing of the sheet not only gives form to the tang, but to the depressed portion or protuberance as well.

The metal or other strip material may be fed in lengths or continuously from a roll and it will be seen that all of the operations are consecutive to produce the finished product, and that any creases or bends in the sheet are ironed out in its passage through the machine by reason of the stripper plates.

In some cases I may dispense with the suction fan below the grid.

In addition to cleaning the sheet of films of the cooling medium which may collect thereon, the cleaning apparatus acts to remove any metal particles and other undesirable matter on the sheet. Thus the hood and grid presenting opposed enlarged openings effectively enclose the s hget while traveling therethrough and prevent any particles from escaping to injureworkmen.

While the above generally described method of punching sheet metal in this particular way and the mechanical elements utilized for that purpose are both novel, various other means for carrying out my method, as well as various modifications of the assembled structural units will be apparent to those skilled in the art and for that reason I intend to limit myself only within the' scope of the appended claims.

This application is a continuation-in-part of my application Serial No. 479,734, filed September 4, 1930, Patent No. 1,843,438, issued February 2, 1932.

I claim:

1. The method of making gasket reinforcing material consisting of a strip of sheet metal having a multiplicity of closely spaced projections formed therefrom extending throughout the area of the strip adapted to be embedded in coextensive layers of gasket material, and each having a relatively elongated and narrow deformable wall portion and a remaining wall portion of less length, which comprises presenting sheet metal material to engagement with a rotating toothed member, depressing and piercing the metal at each point of engagement of a tooth with one side of the sheet and forming openings and walls defining said openings extending laterally from the opposite side of the sheet and continuing the piercing operation and cutting a narrow portion of the metal in advance of each tooth at one side of each opening substantially in the plane of rotation of the teeth and pressing the severed metal laterally from the said opposite side of the sheet and forming an elongated wall at said side of the opening constituting a deformable tang, extending beyond the remainder of the wall of the opening.

2. The method of making gasket reinforcing material consisting of a strip of sheet metal having a multiplicity of closley spaced projections formed therefrom extending throughout the area of the strip adapted to be embedded in coextensive layers of gasket material, and each having a relatively elongated and narrow deformable wall portion and a remaining wall portion of less length which comprises presenting sheet metal material to engagement with a rotating toothed member, depressing and piercing the metal at each point of engagement of a tooth with the sheet and forming openings and walls defining said openings extending laterally from the opposite side of the sheet and continuing the piercing operation and cutting a narrow portion of the metal in advance of each tooth at one side of each opening substantially in the plane of rotation of the teeth and pressing the severed metal laterally of the sheet and forming an elongated wall at said side of the opening constituting a deformable tang and extending beyond the wall portion at the opposite side of the opening.

3. The method of making gasket reinforcing material consisting of a strip of sheet metal having a multiplicity of closely spaced projections formed therefrom extending throughout the area of the strip adapted to be embedded in coextensive layers of gasket material, and each having a relatively elongated and narrow deformable wall portion and a remaining wall portion of less length, which comprises presenting sheet metal material to engagement with a rotating toothed member, depressing and piercing the metal at each point of engagement of a tooth with a sheet and forming depressions having openings and walls extending laterally from the sheet about the openings, and continuing the piercing operation and cutting a narrow portion of the metal in advance of each tooth at one side of the depression, and pressing the severed metal laterally of the sheet from substantially the bottom of the depression and forming an elongated wall at said side of the depression of greater length than the remainder of the wall portion of the depression I and constituting a deformable tang.

engagement with rotating sheet and forming openings and walls defining said openings extending laterally from the opposite side of the sheet and continuing the piercing operation and cutting a narrow portion of the metal in advance of each tooth at one side of each opening substantially in the plane of rotation of the teeth and pressing the severed metal laterally from the said opposite side of the sheet and forming an elongated wall at said side of the opening constituting a deformable tang, extending beyond the remainder of the wall of the opening.

GEORGE T. BALFE.

CERTIFICATE or connection.

Patent No. 1,927,791.

GEORGE T. BALFE.

September '19, 1933.

It is hereby certified that error appears in the printed specification of the above numbered patent requiring correction as-follows: Page 4, line 31, strike out the words "is not removed, but instead formed into a tang" and insert in-. stead wall at one side of the opening elongated and of; and line 39, strike out the words "out in its passage through the machine by reason" and insert instead is not removed, but instead formed into a tang; and that the said Letters Patent should be read with these corrections therein that the same may conform to the record of the case in the Patent Office.

Signed and sealed this 14th day of November, A. D. 1933.

v (Seal) F. M. Hopkins Acting Commissioner 1 of Patents. 

